In the field of household electronic appliances, AV equipment, PC/OA equipment, industrial machinery, and other electronic devices, capacitive type touch switch panels are used as one type of input means to the equipment. FIG. 11 and FIG. 12 show conventional capacitive switch panels in side view. The capacitive touch switch panel 11 shown in FIG. 11 has a structure in which a switch design 12a is produced on a cover 12 made of an acrylic or other resin by printing or laser trimming, sensor electrodes 13 are provided on a printed circuit board (PCB) 14, and the components are laminated together. A control part 15 is mounted on the PCB 14 as well. In the capacitive touch switch panel 11′ shown in FIG. 12, on the other hand, a control part 15 is situated to the outside, and connected to the touch switch panel 11′ via a plastic flexible printed circuit (FPC) 16.
In capacitive touch switch panels having these configurations, when the surface of the cover 12 is touched with a finger, capacitive coupling between a sensor electrode 13 and the finger occurs, and the capacitance of the electrode changes. The sensor electrodes 13 are distributed at multiple locations corresponding to the switch design, and wires are apportioned to the sensor electrodes 13, the sensor electrodes 13 and the control part 15 being connected by the aforementioned wires (in FIG. 12, including the FPC 16). In the control part 15, the amount of change in the capacitance of the sensor electrodes 13 is digitized, determining contact by a finger to have occurred when the value thereof exceeds a predetermined threshold value. In so doing, the control part 15 can detect changes in capacitance of any of the sensor electrodes 13, and can detect which section of the touch with has been touched with the finger.
By way of a capacitive touch switch having fewer parts and improved appearance, there has been proposed one provided with switch electrodes and dummy electrodes comprising metal thin films deposited onto a substrate such as a glass substrate (Patent Document 1). The switch electrodes in this switch are configured to include markings (designs) of prescribed shape. The metal thin films are produced by depositing a material such as aluminum, an aluminum alloy (aluminum-tantalum or the like), niobium, molybdenum, gold, silver, copper, or the like onto a glass substrate comprising soda lime glass or the like, by a method such as sputtering, vapor deposition, or CVD, followed by exposure in a prescribed pattern, and then etching. With the aim of protecting the switch electrodes made of metal thin film, a paste of a black pigment, white pigment, or other coloring pigment mixed into a low-softening point glass frit is printed over the electrodes and baked to form an insulating member (protective layer). As shown in FIG. 5 in Patent Document 1, the printed board and connector terminals on the glass substrate are connected via a FPC and connectors.